To help a cappella sensation Pentatonix celebrate 1 million YouTube subscribers, we invited them to the What’s Trending studio for a performance and chat, to take fans’ questions about the process of creating their next album, details about the upcoming tour, and the journey to being YouTube stars.

“I remember a year ago, seeing some YouTubers with 1 million subscribers and thinking, ‘How nuts would it be to have that many subscribers?’ So now that we’re here and we made it to that milestone, it’s pretty surreal,” Scott Hoying says.

Beat-boxer Kevin Olusola attributes a good amount of their recent views and subscribers to their “Radioactive” collaboration with fellow YouTube musician Lindsey Stirling, as well as their recent “Evolution of Music” video.

And now they’re working on their next album, which Hoying reveals will include a lot more original material and risks with the arrangements.

“It was actually really difficult,” Mitch Grassi says of choosing songs for the album. “We didn’t really decide on a concrete track-listing until recently. We really wanted to pick songs that were best for the group and songs that we thought people wanted to hear, as well as a few surprises.”

Hoying adds, “We think we have four covers that we think would be perfect, and then for originals, we’ve been working on those for a while.”

As a member one of the only a cappella groups breaking into the mainstream, Hoying says that the group feels blessed to be exposing many new listeners to the music genre. “A cappella we feel is such an underrated genre,” he says. “We want to show that it’s actually something really special and really cool and it can be mainstream. And I think that other things like ‘Pitch Perfect’ and ‘The Sing-Off’ and all these mainstream a cappella entertainment is really helping with our goal.”